Ruby on Rails

On Monday 30 January 2012 12:21 PM, Bo Zhao wrote:
> I have a scenario that my user need to upload a image first and then
> assign to another model, so I used a generic model, to upload the file
> first. But I always get a exception of
> ActiveRecord::UnknownAttributeError (unknown attribute: utf8). because
> rails automatically adds a utf-8 field for the form submit.
>
> model:
> <code>
> class AttachedImage< ActiveRecord::Base
> belongs_to :attachable, :polymorphic => true
>
> has_attached_file :image
> end
> </code>
>
> migration:
> <code>
> class CreateAttachedImages< ActiveRecord::Migration
> def change
> create_table :attached_images do |t|
>
> t.string :image_file_name
> t.string :image_content_type
> t.integer :image_file_size
> t.datetime :image_updated_at
> t.references :attachable, :polymorphic => true
>
> t.timestamps
> end
> end
> end
> </code>
>
> And the controller:
> <code>
> class AttachedImagesController< ApplicationController
> def create
>
> @attched_image = AttachedImage.new(params)
>
> respond_to do |format|
> if @attched_image.save
> format.js
> else
> format.js
> end
> end
> end
> end
> </code>
>
> the view part:
> <code>
> <div id="upload-image-dialog">
> <%= form_tag(@attached_image, :method => "POST", :remote => true,
> :html => { :multipart => true }) do %>
> <%= file_field_tag :image %>
> <%= submit_tag("submit") %>
> <% end %>
> <h1 style="display:none">Successfully Uploaded.</h1>
> </div>
> </code>
>
> it's quite straight forward, but every time I submit this form, I will
> get an exception of the utf8 field added automatically by rails.
>
> ActiveRecord::UnknownAttributeError (unknown attribute: utf8):
> app/controllers/attached_images_controller.rb:5:in `new'
> app/controllers/attached_images_controller.rb:5:in `create'
>
> I could not understand that, this shall not be a problem right? We are
> writing @model = Model.new(params) everyday, hope someone could help me
> out and explain what's going on under the hood, thanks!
>
change in the controller

@attched_image = AttachedImage.new(params)

to

@attched_image = AttachedImage.new(params[:attached_image])

if above not working because of form_tag usage

then you have to use custom new like

@attched_image = AttachedImage.new(:image=>params[:image])

this should work.

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